Design of an Annealing Supplemental Surveillance Program for the Palisades Reactor Pressure Vessel

A decision to thermally anneal the Palisades reactor pressure vessel (RPV) was made in 1995 by Consumers Power Company. The anneal is currently planned for 1998 and will be conducted using an indirect gas-fired chamber method which will radiantly heat the RPV beltline region to nominally 454°C (850 °F) for a one week (168 hour) hold time. The recovery of Charpy impact toughness properties after annealing will be ascertained by using a combination of a recovery model developed by Eason et al. and actual validation measurements on Palisades plant-specific surveillance materials. The use of plant-specific surrogate materials (from retired steam generators) and original surveillance program materials requires the development of a supplemental surveillance program focused at both recovery and reirradiation embrittlement. The post anneal re-embrittlement properties are crucial for continued plant operation, and the current use of a lateral shift model for re-embrittlement trending is expected to be conservative. The program also uses reconstituted Charpy specimens and new surveillance capsules following the program format developed for ASTM Standard Guide for In-Service Annealing of Light-Water Cooled Nuclear Reactor Vessels, ASTM E 50986 (1991), 1996 revision currently in ballot. This supplemental surveillance program should provide adequate toughness property definition for the Palisades key materials such that operation can be completed to the end of operating license and beyond if license renewal is pursued.